A device of this kind is known from DE-AS 10 56 083. The winding aid in that device consists of a plurality of clamps arranged on the circumference of the bobbin flange which grasp the transferred thread and hold it for cutting. Devices of this type are not only very expensive to manufacture but also necessitate a change in the bobbin flange. Bobbins, however, are manufactured in large numbers, so that any change in bobbin design should not only be avoided but is rejected by the industry.
The goal of the invention is to provide a winding aid with which the thread being switched from the full bobbin to the adjacent empty bobbin can be held securely on the bobbins without the structural design of the bobbins having to be affected.
To achieve this goal, the invention provides that the winding aid is designed as a pressure element such as a brush or a roller which extends only over the width of the immediately adjacent bobbin flange and abuts only the bobbin flange circumferential surfaces that project radially outward. It is not apparent at the outset that such a stationary pressure element can achieve the stated goal, because it continuously relaxes its hold as the bobbin continues to rotate. Tests have shown, however, that the brief holding effect at the high circumferential speeds of the bobbins is sufficient to prevent the thread from unwinding from the full bobbin. If the thread is cut between the two adjacent bobbins and the full bobbin is ready to be taken away, the thread jumps up and must then be held against the winding. Brushes for this purpose are known from Swiss Patent 239 933 and rollers are known from DE 34 46 691 A1, but these elements merely abut the wound material. Pressure devices of this kind, however, cannot prevent the end of the thread from unwinding during the switch to the empty bobbin because the last turns can be wound up quite tightly against the bobbin flange, where the known roller or the like cannot exert any grip. In addition, the thread must also be held at the flange of the empty bobbin.